On 2023/8/3 22:31, Yi Liu wrote:
Under nested IOMMU translation, userspace owns the stage-1 translation
table (e.g. the stage-1 page table of Intel VT-d or the context table
of ARM SMMUv3, and etc.). Stage-1 translation tables are vendor specific,
and need to be compatiable with the underlying IOMMU hardware. Hence,
compatible
userspace should know the IOMMU hardware capability before creating and
configuring the stage-1 translation table to kernel.
This adds IOMMU_GET_HW_INFO ioctl to query the IOMMU hardware information
(a.k.a capability) for a given device. The returned data is vendor specific,
userspace needs to decode it with the structure mapped by the @out_data_type
field.
As only physical devices have IOMMU hardware, so this will return error
if the given device is not a physical device.
Co-developed-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
drivers/iommu/iommufd/main.c | 79 ++++++++++++++++++++++++++++++++++++
include/uapi/linux/iommufd.h | 36 ++++++++++++++++
2 files changed, 115 insertions(+)
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 94c498b8fdf6..a0302bcaa97c 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -17,6 +17,7 @@
#include <linux/bug.h>
#include <uapi/linux/iommufd.h>
#include <linux/iommufd.h>
+#include "../iommu-priv.h"
#include "io_pagetable.h"
#include "iommufd_private.h"
@@ -177,6 +178,81 @@ static int iommufd_destroy(struct iommufd_ucmd *ucmd)
return 0;
}
+static int iommufd_zero_fill_user(void __user *ptr, size_t bytes)
+{
+ int index = 0;
+
+ for (; index < bytes; index++) {
+ if (put_user(0, (uint8_t __user *)(ptr + index)))
+ return -EFAULT;
+ }
+ return 0;
+}
+
+static int iommufd_get_hw_info(struct iommufd_ucmd *ucmd)
+{
+ u32 hw_info_type = IOMMU_HW_INFO_TYPE_NONE;
+ struct iommu_hw_info *cmd = ucmd->cmd;
+ unsigned int length = 0, data_len;
+ struct iommufd_device *idev;
+ const struct iommu_ops *ops;
+ void __user *user_ptr;
+ void *data = NULL;
+ int rc = 0;
+
+ if (cmd->flags || cmd->__reserved || !cmd->data_len)
+ return -EOPNOTSUPP;
+
+ idev = iommufd_get_device(ucmd, cmd->dev_id);
+ if (IS_ERR(idev))
+ return PTR_ERR(idev);
+
+ user_ptr = u64_to_user_ptr(cmd->data_ptr);
+
+ ops = dev_iommu_ops(idev->dev);
+ if (!ops->hw_info)
+ goto done;
+
+ data = ops->hw_info(idev->dev, &data_len, &hw_info_type);
+ if (IS_ERR(data)) {
+ rc = PTR_ERR(data);
+ goto out_err;
Can kfree() handle a ERR_PTR input? I am afraid not,
/**
* kfree - free previously allocated memory
* @object: pointer returned by kmalloc() or kmem_cache_alloc()
*
* If @object is NULL, no operation is performed.
*/
void kfree(const void *object)
{
struct folio *folio;
struct slab *slab;
struct kmem_cache *s;
trace_kfree(_RET_IP_, object);
if (unlikely(ZERO_OR_NULL_PTR(object)))
return;
So, perhaps we should add
data = NULL;
before
goto out_err;
?
+ }
+
+ /* driver has hw_info callback should have a unique hw_info_type */
+ if (WARN_ON_ONCE(hw_info_type == IOMMU_HW_INFO_TYPE_NONE)) {
+ rc = -ENODEV;
+ goto out_err;
+ }
+
+ length = min(cmd->data_len, data_len);
+ if (copy_to_user(user_ptr, data, length)) {
+ rc = -EFAULT;
+ goto out_err;
+ }
+
+done:
+ /*
+ * Zero the trailing bytes if the user buffer is bigger than the
+ * data size kernel actually has.
+ */
+ if (length < cmd->data_len) {
+ rc = iommufd_zero_fill_user(user_ptr + length,
+ cmd->data_len - length);
+ if (rc)
+ goto out_err;
+ }
+
+ cmd->data_len = length;
+ cmd->out_data_type = hw_info_type;
+ rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+
+out_err:
+ kfree(data);
+ iommufd_put_object(&idev->obj);
+ return rc;
+}
+
Others look good to me, feel free to add:
Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
after above are addressed.
Best regards,
baolu
